The present invention relates to a storage battery separator characterized in that the same comprises a mixture of phenol resin, polyolefin resin and inorganic powder, and containing the phenol resin 2-50% based on the mixture.
The phenol resin in the storage battery separator is one or more selected from a novolak type, a resol type and a modified resin of these types.
The polyolefin resin of said storage battery separator is one or more selected from polyethylene, polypropylene, polybutylene, copolymers thereof and a polymer blend thereof with a weight average molecular weight thereof of 50,000 or more, in a ratio to the mixture of 10-60% by weight.
The inorganic powder of said storage battery separator is one more selected from silica, silicate such as calcium silicate, alumina, calcium carbonate, kaolin, talc, diatomaceous earth, carbon black, glass fibrous powder etc., in a ratio of 35-70% by weight to the mixture.
The storage battery separator may be made by mixing a phenol resin in the amount of 2-50% by weight, polyolefin resin in the amount of 10-60% by weight and inorganic powder in the amount of 35-85% by weight and the resultant composite of 100 parts, and an organic liquid of 50-200 parts are then mixed, and the resultant mixture is molded to form a sheet, and the organic liquid is extracted from the sheet, and said sheet is then dried.
In said process of manufacturing a storage battery separator the phenol resin may be used in the form of a powder.